I just posted this but KL's MD-11 fleet is only 6.5 years old on average. Your looking at another 7-10 years before you will start seeing replacements.

If they move to the proposed 7 block system then you will probably see some smaller a/c but if they stay as is (5 block) maybe they will throw some new 777 aircraft on. And they will probably be leases from someone like the ILFC not direct orders (like the current 767-300ER a/c). Right now KL is looking for some replacements for their 767's whose leases are going to expire in a few years.

KLM is unlikely to buy airbus. They are standardising ever more on Boeing (they used to have A310s, those were all sold years ago and replaced with 737s).
What may happen is transferral of the MD11s to Martinair in exchange for their 767s (speculation only, based on suggestions that KLM is turning Martinair into their cargo division and the fact that MD11s are very popular for cargo conversion...).